Urgently need your support to solve the device failure problem

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Hi PI_Experts,


We selected DER-430 Reference design, which is 7.8W LED Driver designed using LYT2004D with Input range - 90-270VAC and Output voltage 62VDC/ 130mA.

We designed transformer using EE-16 core [Ballasat-CC]. By only replacing transformer in DER-430 board, turn on LED driver with no-load gives output voltage 93VDC, With preload resistor 1ME. And by connecting LED load, with input 60VAC Driver output is blinking but input higher than 170VAC, driver gives constant output voltage 56VDC and current 30mA,after few minutes the device LYT2004D failed, input fuse burnt.

LED Board details- 20 LEDS of VF=3.1V/IF=150mA is connected in series.

Driver o/p= 20x3.1= 62VDC

Driver output current = 130mA

Transformer design spread sheet is attached to the post for your reference.

We use input bulk capacitors C1 and C2 10uF/450V, not used inductors L1, L2 and hence not placed resistor R1 and R2.

We need your kind support to sort out the problem. 


Thanks and Regards,


첨부 파일Size
EE-16, 7.8W.pixls36.91 KB

Hi PI.Experts,

One mistake in transformer design spread sheet is Device Chosen is in Auto and selected LYT2004K/E, but we used LYT2004D package. Now by selecting LYT2004D complete transformer contruction will varies. Please confirm due to this device failure will occurs.

Thanks and regards,



Please check the transformer design to replace in DER-430 reference design instead of EE-13 core, We selected EE-16 core and output voltage= 64VDC, output current= 0.12A, NFB= 18turns, CIN= 20uF/450V, LP_Tolerence= 4% and BM_Target= 2500 GUASS. 

And we will vary R7, R8 and R9 values. 

Can we replace the designed EE-16 transformer in DER-430 or need to change any other components in the board.

Transformer design spread sheet is attached to the post for your kind information.


Thanks and Regards,


LYT2004D, EE-16.pixls36.91 KB

Can you use an e-load first to determine your CV/CC point? DER-430 was designed for a 60V CV point. For CC operation, the LED string has to be lower than 60V or your won't get the correct output current.

Using EE16 on DER-430 is OK but again the LED string should be less than 60V, assuming you used the same component values on the report.

If you need to operate at 62V in CC region, the PIXLS design should have a VO of around 68V. Please be careful about the maximum VDS as this could damage the IC if the VDS exceeds 725V. Increase the switching frequency to reduce the VDS stress.

Please monitor the VDS as you increase the input voltage and ensure that the stress level is within limit.


Hi Crumb,

We follow your suggestions and do the necessary changes in the design.

Thanks alot.